INVOLVEMENT OF MULTIPLE KINASES IN NEUTROPHIL ACTIVATION

Production of reactive oxygen metabolites by the NADPH oxidase is an e ssential mechanism underlying the microbicidal role of phagocytes. Rec eptor-mediated activation of the oxidase was originally thought to be mediated by calcium and/or by protein kinase C (PKC). However, recent evidence suggests that additional signalling pathways exist. In this a rticle the possible role of tyrosine phosphorylation is discussed. In addition, results obtained using an in vitro kinase renaturation assay are described. The latter assay revealed the existence of at least fo ur serine/threonine kinases that are activated in cells stimulated wit h chemoattractants. One of these, of molecular weight 41,000 was ident ified as a member of the ERK or MAP-kinase family. The existence of mu ltiple, possibly redundant or synergistic signaling pathways is consid ered.